Diestock for use in threading tubes, bars, and like work



June 5, 1951v A. TREVENA 2,556,015

DIESTOCK FOR USE IN THREADING TUBES, BARS AND LIKE WORK Filed Dec. 15,1948 :5 Sheets-Sheet 2 32 3 26 \J Z4- Z3 Z7 25 5 I7 13 21 J I 4 1 4o 43a \O wvm-ran W A. TREVENA June 5, 1951 DIESTOCK FOR USE IN THREADINGTUBES, BARS AND LIKE WORK 3 Sheets-Sheet 5 Filed Dec. 15, 1948 I I Inazm's Patented June 5, 1951 DIESTOCK FOR USE IN THREADING TUBES, BARS,AND LIKE WORK Arthur Trevena, Birmingham, England, assignor to J.Brockhouse & Company Limited, West Bromwich, England, a British companyApplication December 15, 1948, Serial No. 65,377 In Great BritainDecember 27, 1947 13 Claims.

This invention relates to die stocks for use in L threading tubes, barsand like work and refers to that kind of die stock which comprises abody carrying the screwing dies and means for displacing the diestowards and away from the work so, that the threading can be carried outin a pluwould be required, if the thread was initially cut to the fulldepth.

As hitherto constructed the dies have been mounted for radial movementin relation to the body and have been advanced towards or away from thework by means of a cam member mounted rotatably on the body and providedwith a cam face adapted to engage with .a further face on each of thedies so as to efiect their displacement, and the cam member and the bodyhave been provided with co-operating scale mark-..

ings adapted to register when the dies are in the correct position forcutting a thread to the full depth.

With such an arrangement the position of the dies for effecting a threadcut of less than the full depth has to be estimated from scale reading,while the position .for cutting the't-hreads to the full depth isdependent upon accurate reading of the scale by the operator and if thisis read inaccurately or carelessly an improper thread will result.

The primary object of the present invention is to provide an improvedarrangement in which the dies are locked positively both in a positionfor cutting a thread to the full depth and also in an intermediateposition for cutting the thread to less than the full depth.

A further object of the invention is the provision of means for rapidlydisplacing th dies in either of their operative positions into and outof operative engagement with the work.

A further object or the invention is the provision of a die stock inwhich such locking means and release means are not subjected toanyappreciable thrust tending to displace them out of A their operativepositions in consequence of the operative engagement between the diesvand the Work to be threaded during the threading operation.

' Other objects of the invention will be apparent from the followingdescription of the invention and the claims appendent thereto and thedrawings accompanying the specification, in which:

Figure 1 is a plan view of one form ofa die stock constructed inaccordance with the present invention and intended for use in threadingthe exterior of .a bar or tube.

Figure 2 is a side view of the same construction looking in thedirection of the .arrow 2-2 in Figure 1.

Figure 3 is a part sectional view on the lines 3-3 of Figure 1.

Figure 4 is a cross sectional view of part of the same constructionillustrating the mechanism provided for varying the operative positionof the dies, the mechanism being depicted in a position in which thedies are out of operative engagement with the work.

Figure 5 is a sectional View on the line 5-5 of Figure 4 showing themechanism in the position in which the dies are out of operativeengagement with the work.

Figure 6 is a view similar to Figure 5 showing the mechanism in aposition in which-the dies are in full operative engagement with thework for cutting a thread to the full depth. 1 t

Figure 7 is a view similar to Figure 6 in whic the mechanism is in aposition such that the dies may cut a thread to half the full depth.

Referring to the drawings the die stock there illustrated comprises ahollow body I!) of cylindrical form provided at four symmetricallydisposed positions with a radially extending die opening H, in each ofwhich is radially slidable one of the four thread cutting dies l2 whichare provided, the dies being formed on their inner ends with the usualthread cutting teeth [3.

Intermediate its upper and lower ends the body It is formed with aradial outwardly extending flange I4 which terminates in an axialupwardly extending lip I5 so as to provide an annular space 16, abovewhich is rotatably mounted an annular die displacing member I lconveniently in the form of a plate, the under face of which near itsperiphery engages rotatably with the upper edge of the aforesaid lip 15,while the outer face of the die displacing member is flush with theadjacent and of the cylindrical body and is retained therein by aretaining ring 18 havin a flange which screws .into the interior ofthis. end .of the body. o

The die displacing member is formed on its under face with .foursymmetrically disposed arcuate shaped projections l9 which are eccentricthe operating member spindle 21. i has limited axial movement in anupward direccorresponding to twice its throw.

die locking position depicted inFigures 6 and '7 in which the lever ismore or less tangential relative to the body and in which the dies arein operative engagement with the work.

Means are provided for rotating the body of the die stock about the axisof the work to be threaded, which work may for instance comprise I around metal bar or a tube.

The member I1 is formed at one side with'a peripheral part-circularflange 2! in which is formed an arcuate'slot 22 through which projectsan axially extending externally threaded: guide sleeve 23, which sleeveengages the slot nonrotatably but slidably so that the die displacing'member I! can be turned relative to the guide sleeve to an extentcorresponding to the length of the slot 22, the member I! being normallyreleasably locked against such turning movement by a locking nut 24 onthe exterior of the sleeve, the locking nut engaging the flanged part 2|of the die displacing member through the medium of a washer 25 andcarrying a suitable operating arm 26. I

Mounted rotatably within the interior of the I guide sleeve 23 is anoperating member 2! in the form of a spindle carrying at its lower endan eccentric constitutedby a pin 28, the axis of which is eccentric inrelation to the axis of rotation of The spindle 27 threaded, such meanscomprising a die stock rotating member 44 of annular form which extendsaround the exterior of the body I!) intermediate the upper and lowerends thereof, the

rotating member being operatively connected to the body by means of oneway ratchet mechanism. of known formindicated generally at 45 in Figure3 and being provided with a pair of diametrically opposed sockets 43 forthe reception of turning bars, the inner ends of which are indicated at41 in Figure 1.

Centering means of known form comprising a plurality of symmetricallydisposed radially slidable centering elements 43 are further provided,

' such elements being adapted at their inner ends to engage rotatablywith the exterior of the work below the part to be threaded and beingcapable of being displaced radially in the known manner by a ring 49mounted rotatably on the lower end of the die body, the ring having athreaded connection indicated at 5|! with the elements 48 and beingcapable of being turned by handle 5|.

The upperface of the die displacing member l1 and the retaining ring l3forming part of the ,body ID are provided .with setting marking intionin relation to the sleeve 23, which axial V movement is controlled andlimited by a compression spring 29' disposed in an enlarged part of thesleeve near its lower end and acting between the innerend of such partand a shoulder 30. on the spindle adjacent the eccentric pin 28.

The spindle 2! is provided at its upper end with an operating knob 3|whereby it may be rotated,

but rotation of the spindle is normally prevented l by providing theknob on opposite sides thereof with a pair of dependent ears 32 whichnormally engage in diametrically disposedrecesses formed in the sleeveend so asto lock the spindle in such new position, such rotation of thespindle serving to displace the eccentric pin 28 through a distance Theeccentric pin 28 works within a correspondingly shaped hole 33 providedon the inner end of a release lever 34 which is formed immediately onthe outer side of such hole 33 with a second parallel hole 35 which islikewise axial u with respect to the cylindrical body, and into thishole 35 extends rotatably a pivot pin 33 mounted fixedly on the outerend of a radially'disposed plunger 31, which plunger is radiallyslidable in a pair of radially spaced slots 38, 39 formed respectivelyone in the cylindrical wall of the body I0 and the other in the lip 5.

The release lever 34 is hollow intermediate the end, and adetent in theform of a ball 43, which engages with one of a pair of recesses 43a,spaced circumferentially around the pivot pin so as to locate therelease lever 34 in either of two positions, namely a release positiondepicted in Figures 4 and 5 in which the. lever is radial with respectto the body and work axis as well as, i a

dicated generally at 52, which markings indicate the relative positionof the die displacing memher I! and the body for the cutting to the fulldepthof screw threads appropriate to the external diameter of the work,Which is being op erated on.

' structed as above described is as follows.

In the aforementioned description the expres sions upper and lower"where used are employed merely to denote that part of the die stockwhich is situated nearest and furthest respectively from the threadingdies. V

The mode of operation of a die stock con- The arm 26 which serves tolock the threaded guide sleeve 23 and spindle 2'! to the die displacingmember I1 is initially released thereby permit ting of the diedisplacing member being pivoted relative to the body It until theappropriate setting markings of the dies for the particular work to bethreaded are opposite to one another on the the diev displacing memberIT in this position to the guide sleeve 23 and hence to the spindle 21.

The release lever 34 is then displaced into the release positionillustrated in Figures 4 and 5 so as to displace the dies radially,outwardly into a position in which they are incapable of operativeengagement with work of external diameter corresponding to the abovesetting of the die displacing member. 7

Assuming that it is now desired to cut the threads initially to half thefull depth the operating knob 3| is actuated to displace the spindle 21axially of the sleeve 23, so as to disengage the ears 32 from therecesses in the upper end of the sleeve 23 and permit of the spindlebeing turned into a position corresponding to the half depth a threadcutting position of the dies.

Such position is conveniently readily observable by providing the upperface of the knob 3| with the markings full and half, so that when.

the release lever 34 is on the operators left hand and the word halfappears inv areadable poimers for cutting the threads to the half depth,while with the spindle rotated through l80 so that the word full appearsin a readable position as shown in Figure l, the dies are in theposition for cutting threads to the full depth.

With the spindle 21 adjusted to the half cutting position the die stockis disposed over the end of the work to be threaded with the diesopposite to the particular part of the work upon which the threads areto be cut and the elements 48 are brought into guiding engagement withthe exterior of the work below the part to be threaded.

The release lever 34 is now displaced from the release position depictedin Figures 4 and 5 to the operative position depicted in Figures 6 and'7 such movement serving to bring the eccentric pin 28 and operatingspindle 21 from a position in which they are situated on the radiallyinner side of the pivot pin 36 to a position in which the eccentric 33together with the axis of the spindle 21' are spaced substantiallycircumferentially with respect to the pivot pin 36. Owing to the factthat the spindle 21 can only move bodily about the axis of rotation ofthe body, in

36 is constrained to be displaced, bodily in a radial direction by theplunger 31, the operatin spindle 2'! is displaced in a circumferentialdirection by a distance corresponding substantially to the distancebetween the axis of the spindle and the axis of the pivot pin 36 and acorresponding pivotal movement of the die displacing member I iseffected by reason of the fact that the guide sleeve 23 carrying thespindle is locked to the member 11. In consequence of this displacementof the member I! the cams l9 thereon efiect operative displacement ofthe dies in an inward direction so as to bring them into the half threaddepth cutting position.

Threading of the work to half depth is now effected by rotating the diestock bodily in the known way.

When the desired axial length of thread to half depthhas been cut thedie stock is turned in the opposite direction back to its initialthreading position in relation to the Work and the. operating spindle 21is turned through 180 in relation to the sleeve 23 so as to bring itinto a position corresponding to that of full thread depth.

Such movement of the operating spindle 21 serves to displace the axis ofthe spindle bodily in a circumferential direction relative to the axisof the eccentric pin 28 which during such movement of the spindle pivotswithin the hole 33 in the inner end of the release lever so that. theaxis of the spindle is brought from a position in which as shown inFigure 7 it is situated substantially between the axes of the eccentricpin 23 and pivot pin 35 to a position in which as shown in Figure 6 theaxis of the operating spindle is disposed on the side of the eccentricpin axis which is remote from. the axis of the pivot pin. In otherwords, the spindle 21 is between the two cutting positions by a distancecorresponding substantially to twice the eccentricity of the eccentricpin 38., thereby pivoting the die displacing member I! relative to therelease lever 34 and relative to the. body III by a distance sufiicientto cause the cams [9 to displace the dies l2 inwardly into a positionfor cutting the threads to the full depth, whereupon the above describedthreading operation is repeated to obtain the finished threads on thework to the full depth desired.

The release lever 34 is then pivoted from an operative position to therelease position thus pivoting the die displacing member H in thereverse direction from the position depicted in Figure 6, to thatdepicted in Figure 5 and brineing the dies completely out of operativeengagement with the work, whereby the die stock may be rapidly removedfrom the work by a simple axial movement.

The maximum circumferential displacement of the operating spindle 2! inconsequence of its rotation through 180 is ensured by so displacing thecars 32 on the operating knob 2'! in relation to the eccentric pin 28 asto ensure that with the release lever in the operating position shown inFigures 6 and 7 and ears 32 in engagement with the recesses in the endof the sleeve 23; the axes of the eccentric pin, pivot pin 36 andspindle 21 are substantially in line, which line in fact iscircumferential with respect to the axis of rotation of the diedisplacing member.

The distance between the axis of the pivot pin 38 and the axis of theeccentric pin 28 is made greater than the distance corresponding totwice the throw of the eccentric pin 28, thereby ensuring that when thelever 34 is displaced from one, to the. other of its two positions thepivotal movement of the die displacing member I! is more than twice themovement obtained by merely rotating the spindle 21 between the twothread cutting positions of the dies.

By constructing the parts so that with the release lever 34 in theoperative position the axes of the spindle 2T, eccentric pin 28 andpivot pin 36 all lie substantially on a line which is circumferentialwith respect to the axis of pivoting of the die displacing member ll,any resultant force produced by the reaction during threading betweenthe dies l2 and the die displacing member lltending to pivot theserelative to the body l0 acts on the pivot pin 36 in a direction at:right angles to the direction of sliding of the plunger 31 so that thereis no resultant force tending to displace this radially.

Furthermore, any such force tending to pivot the member [1 which acts onthe eccentric pin 28 is not. transmitted to any appreciable degree tothe operating spindle 2'! so as to tend to rotate it, by virtue of thefact that the axes of the pin 28 and. spindle 21 are situated on a linewhich is circumferential in respect to the, axis of rotation of the diedisplacing member ll.

Thus both the release mechanism and the die locking mechanism may bemade of relatively light construction and are not subjected toappreciable stresses in consequence of the. actual threading operation.

Thus there is provided a construction in which the dies are positivelylockedby the operating member in the two thread cutting positions and nocareful observance of a scale is required on the part of the operatorwhen cutting'to less than full thread depth, it being necessary merelyto actuate this member in the manner described after cutting to halfdepth for the'purpose of effecting the final cutting of the threads tofull depth.

It is thus ensured that the threads are al ways out exactly to the halfand full depths required so that the construction "is quite fool proof.7

for rotating said body about the axis of the work to'be threaded, aplurality of threading die elements mounted on said body for movementrelative to said body towards and away from theaxis of rotation of thebody, a die element displacing member mounted on said body for pivotalmovement relative to said body, means operatively connecting saiddisplacing member to the die eiements, an operating member carried bysaid die displacing member so as to pivot therewith relative to thebody, said operating member being mounted for rotary movement relativeto the displacing member, an eccentric on said operating member, aplunger member mounted on the body for sliding movement relative to thebody in a direction transverse to the direction of movement of theoperating member when pivoted with the die displacing member, a dieelement release lever mounted for pivotal movement relative to saidplunger, means for releasably locking 'said lever relative to saidplunger, said lever releasably lock said operating member in either oftwo rotational positions in relation to the die element displacingmember so as positively to lock said displacing member with its dieelements in a position for cutting a thread to the full depth and alsoin an intermediate position for cutting the thread to less than the fulldepth.

2. A die stock for use in forming a screw thread comprising incombination a hollow body, means for rotating said body about the axisof the work to be threaded, a plurality of threading die elementsmounted on said body for movement relative to said body towards and awayfrom the axis of rotation of the body, a die element displacing membermounted on said body for pivotal movement relative to said body, aboutthe axis of rotation thereof, means operatively connecting saiddisplacing member to the die elements, an operating spindle carried bysaid die displacing member so as to pivot therewith relative to thebody, said operating spindle being mounted for rotary movement relativeto the displacing member about an axis parallel to the axis of rotationof the body, an eccentric on said operating spindle, a plunger membermounted on the body for sliding movement radially of said body axis ofrotation, a die element release lever mounted for pivotal movementrelative to said plunger, means for releasably locking said leverrelative to said plunger, said lever having an opening therein spacedalong the length of said lever relative to "said lever pivot, saideccentric working within said opening in said lever, and means adaptedto positively and releasably lock said operating spindle in either oftwo rotational positions in a relation to the die element displacingmember so as positively to lock said displacing member with its dieelements in a position for cutting a thread to the full depth and alsoin an intermediate position for cutting the thread to-less than the fulldepth. V V

3. A die stock for use in forming a screw thread comprising incombination a hollow body, means for rotating said body aboutthe axis ofthe work to be threaded, a plurality of threading die elements mountedon said body for movement rela- V tive to said body towards and awayfrom the axis of rotation of the body, a die element displacing membermounted on said body for pivotal movement relative to said body aboutthe axis of rotation thereof, means operatively connecting saiddisplacing member to the die elements, a sleeve carried by saiddisplacing member so as to pivot therewith relative to the body, saidsleeve extending parallel to the axis of rotation of said body, anoperating spindle mounted for rotation within said sleeve, an eccentricon said operating spindle and working within a bearing associated withthe body, said sleeve having locking means engageable with furtherlocking means on said operating spindle to lock the spindle againstrotation relative to said sleeve, said spindle being displaceableaxially of the sleeve to effect disengagement of said locking means,spring means releasably retaining said spindle in its locked position,said locking means serving to, lock said spindle in either of tworotational positions in relation to the die element displacing member soas positively to lock said displacing member with its .die elements in aposition for cutting a thread to the full depth and also in an inter-1mediate position for cutting the thread to less than the full depth.

4. A die stock for use in forming a screw thread comprising incombination a hollow body, means for rotating said body about the axisof the work to be threaded, a plurality of threading die elementsmounted on said body for movement relative. to said body towards andaway from the axis of rotation of the body, a die element displacingmember mounted on said body for pivotal movement relative to said bodyabout the axis of rotation thereof, meansoperatively connecting saiddisplacing member to the die elements, a sleeve carried by saiddisplacing member so as to pivot therewith relative to the body, saidsleeve extending parallel to the axis of rotation of said body, anoperating spindle mounted for rotation within said sleeve, an eccentricon said operating spindle, a plunger member mounted-on the body forsliding movement radially of said body axis of rotation, a die elementrelease lever mounted for pivotal movement relative to said plunger,means for releasably locking said lever relative to said plunger, saidlever having an opening therein spaced along the length of said leverrelative to said lever pivot, said eccentric working tional positions inrelation to the die element displacing member so as positively to locksaid displacing member with its die elements in a position for cutting athread to the full depth and also in an intermediate position forcutting the thread to less than the full depth.

5'. A die stock for use in forming a screw thread comprising incombination a hollow body, means for rotating said body about the axisof the work to be threaded, a plurality of threading die ele'e mentsmounted on said body for movement relative to said body towards and awayfrom the axis of rotation of the body, a die element displacing membermounted on said body for pivotal movement relative to said body aboutthe axis of rotation thereon, means operatively connecting saiddisplacing member to the die elements, said die element displacingmember having an .arcuate slot centred on the axis of rotation of saidbody, a sleeve mounted in said slot so as to pivot with said displacingmember relative to the body, said sleeve being adjustable along thelength of said slot, means for releasably locking said sleeve in anyposition along the slot relative to the displacing member, said sleeveextending parallel to the axis of rotation of said body, an operatingspindle mounted icr rotation within said sleeve, an eccentric on saidoperating spindle, a plunger member mounted on the body for slidingmovement radially of said body axis of rotation, a die element releaselever mounted for pivotal movement relative to said plunger, means forreleasably locking said lever relative to said plunger, said leverhaving an opening therein spaced along the length of said lever relativeto said lever pivot, said eccentric working within said opening in saidlever, and

means adapted to positively and releasably lock for rotating said bodyabout the axis of the work to be threaded, a plurality of threading dieelemerits mounted on said body formovement relative to said body towardsand away from the axis of rotation of the body, a die element displacingmember mounted on said body for piv- .otal movement relative to saidbody about the axis of rotation thereof, means 'operatively conne'ctingsaid displacing member to the die elements, said die element displacingmember having an arcuate slot centred on the axis of rotation of saidbody, a sleeve mounted in said slot so as to pivot with said displacingmember relative to the body, said sleeve being adjustable along thelength of said slot, means for releasablylocking said sleeve in anyposition along the slot relative to the displacing member, said sleeveextending parallel to the axis of rotation of said body, an operatingspindle mounted for rotation within said sleeve, an eccentric on saidoperating spindle, a plunger member mounted on the body for slidingmovement radial-1y of said body axis of rotation, a die element releaselever mounted for pivotal movement relative to said plunger, means forreleasably locking said lever relative to said plunger, said leverhaving an opening therein spaced along the length of said lever relativeto said lever pivot, said eccentric working within said opening in saidlever, said sleeve having locking means engageable with further lockingmeans on said operating spindle to lock the spindle against rotationrelative to said sleeve, said spindle being dis-placeable axially of thesleeve to effect disengagement of said looking means, spring meansreleasably retaining said spindle in its locked position, said lockingmeans serving to lock said spindle in either of two rotational positionsin relation to the die eleme'nt displacing member so as positively tolock said displacing member with its die elements in a position forcutting a thread to the full depth and also in an intermediate positionfor cutting the thread to less than the full depth.

7. A die stock for use in forming a screw thread comprising incombination a hollow body, means for rotating said body about the axisof the work to be threaded, a plurality of threading die elementsmounted on said body for movement relative to said body towards and awayfrom the axis of rotation of the body, a die element displacingmembermounted on said body for pivotal movement relative to said body aboutthe axis of rotation thereof, means operatively connecting saiddisplacing member to the die elements, said die element displacingmember having anar'cuate slot centred on the axis of rotation'of saidbody, a sleeve mounted in said slot so as to pivot with said displacingmember relative to the body, said sleeve being adjustable along thelength of said slot, means for releasably locking said sleeve in anyposition along the slot relative to the dis placing member, said sleeveextending parallel to the axis of rotation of said body, an operatingspindle'mounted for rotation within said sleeve, an eccentric on saidoperating spindle, a plunger member mounted on the body for slidingmove-lment radially of said body axis of rotation, a pivot pin on theouter end of said plunger extending transversely thereto and rigidtherewith, a hollow the element release lever mounted on said pivot pin,a spring loaded detent within said lever adapted to engage with saidpivot pin and lock the lever in an operative position, said lever havingan opening therein spaced along" the length of said lever relative tosaid lever pivot, said eccentric working within said opening in saidlever, said sleeve having locking means an 'gageable with furtherlocking means on said opcrating spindle to lock the spindle againstrotation relative to said sleeve, said spindle being displaceableaxially of the sleeve to effect disemgagement of said locking means,spring means releasably retaining said spindle in its locked position,said locking means serving to lock said spindle in either of tworotational positions in relation to the die element displacing member soas positively to lock said displacng member with its die elements in aposition for cutting a thread to the full depth and also in .anintermediate position for cutting the thread to less than the run depth.

8; A die stock for use in forming a screw thread comprising incombination a hollow body, means for rotating said body about the axisor the work to be threaded, a plurality of threading die elementsmounted on said bodylfor movement relative to said body towards and away.from the axis of rotation of the body, a die element displacing membermounted on said body for pivotal movement relative to said body aboutthe of rotation thereof, means operatively connecting said displacingmember to the die elements, an operating spindle carried by said diedisplacing member so as to pivot therewith relative to the body, saidoperating spindle being mounted for rotary movement relative to thedisplacing member about an axis parallel to the axis of rotation of thebody, an eccentric on said operatingspindle, a plunger member mounted onthe body for sliding movement radially of said body axis of rotation, adie element release lever mounted for t a, l, 11 l pivotal movementrelative to said plunger, means for releasably looking said leverrelative to said plunger, said lever having an opening therein spacedalong the length of said lever relative to said lever pivot, saideccentric working within said opening in said lever, means adapted topositivelyand releasably lock said operating spindle in either of tworotational positions in relation to the die element displacing member soas posi- .tively to lock said displacing member with its .die elementsin a position for cutting a thread to the full depth and also in anintermediate position for cutting the thread to less than the tolldepth, said release lever being adapted in one pivotal position relativeto said plunger and said operating spindle to secure the die elementdisplacing member in a position in which the .dies are adaptedoperatively to engage with the work, said operating spindle in either ofits operative positions, said pivot between the release lever and theplunger, and said eccentric in 7 either operative position of saidspindle having their axes disposed on a line circumferential withrespect to the axis of the body.

9. A die stock for use in forming a screw thread, comprising incombination a hollow body element, means for rotating said body elementabout the axis of the work to be threaded, a plurality of threading diesmounted on said body element for movement relative to said body elementtowards and away from the axis of rota- .tionof the bodyelement, a camelement mounted rotatably on said body element and having cam engagementwith said threading dies so as to displace the same towards and awayfrom the axis of rotation of the body element, a die release .levermountedpivotally on a pivot member carried by one of said two elements,said lever being operably connected to the other element so that saidlever is adapted to be turned about said pivot member to displace saidcam and body ele- -ments relatively between die operating and dierelease positions for the purpose of immediately effecting displacementof the dies into and out of operative position in relation to the work,means independent of said die release lever for displacing said pivotmember bodily in relation to the element on which it is mounted andbetween two operative positions corresponding to difierent predeterminedthread cutting depths,

said lever being adapted to co-act with said pivot member intransmitting said bodily movement of said pivot member to displace saidbody and cam elements relatively between two operative positions, andmeans for locking said pivot member against bodily displacement inrelation to the element on which it is mounted in each of ,said twooperative positions.

element for movement relative to said body element towards and away fromthe axis of rotation ing its axis parallel, but eccentric to the axis ofpivoting of said operating member, a die release lever mounted pivotallyon the pivot pin, said die release lever being operatively connected tothe body element so that said lever is adapted to be turned about saidpivot pin to displace said cam and body elements relatively between dieoperating and die release positions for the purpose of immediatelyeiTecting displacement of the dies into and out of operative position inrelation to the work, said operating member being adapted when pivotedin relation to the cam element upon which it is mounted, to displacesaid pivot pin bodily in relation to the cam element between twooperative positions corresponding to different predetermined threadcutting depths, said die release lever being adapted to co-act with saidpivot pin in transmitting said bodily movement thereof to displace saidbody and cam elements relatively between said two operative positions,and means for locking said operating member against. pivotal movementrelative to the cam element in each of said two operative positions.

11. A die stock for use in forming a screw thread, comprising incombination a hollow body element, means for rotating said body elementabout the axis of the work to be threaded, a plurality of threading diesmounted on said body element for movement relative to said body elementtowards and away from the axis of rotation of the body element, a camelement mounted rotatably on said body element and having cam engagementwith said threading dies so as to displace the same towards and awayfrom the axis of rotation of the body element, an operating membermounted upon the cam element for pivotal movement relative thereto aboutan axis parallel to, but spaced from the axis of rotation of the camelement on'the body element, a pivot pin carried by said operatingmember having its axis parallel, but eccentric to the axis of pivot- 1ing of said operating member, a plunger at the of the body element, acam element mounted side of said body element adjacent said operatingmember and mounted slidably on said body element for movement in adirection transverse to the direction of movement of said operatingmember when the cam element is pivoted on the bodyelement, a die releaselever mounted pivotally on the pivot pin, said die release lever beingpivoted to said plunger for pivotal movement about an axis parallel to,but spaced from the axis of pivoting of the plunger relative to thepivot pin so that said lever is adapted to be turned about said pivotpin to displace said cam and body elements relatively between dieoperating and die release positions for the purpose of immediatelyeffecting displacement of the dies into and out of operative position inrelation to the work, said operating member being adapted when pivotedin relation to the cam element upon which it is mounted, to displacesaid pivot pin bodily in relation to the cam element between twooperative positions corresponding to different predetermined threadcutting depths, said die release lever being adapted to co-act with saidpivot pin in transmitting said bodily movement thereof to displace saidbody and cam elements relatively between said two operative positions,and means for locking said operating member against pivotal movementrelative to the cam element in each of said two operative positions.

12. A die stock for use in forming a screw thread, comprising incombination a hollow body element, means for rotating said body elementabout the axis of the work to be threaded, a phi- 13 rality of threadingdies mounted on said body element for movement relative to said bodyelement towards and away from the axis of rotation of the body element,a cam element mounted rotatably on said body element and having camengagement with said threading dies so as to displace the same towardsand away from the axis of rotation of the body element, a sleeve mountedon said cam element having its axis parallel to the axis of rotation ofsaid cam element on said body element, said sleeve being slidable bodilyrelative to said cam element about the axis of rotation of said camelement, said sleeve being held against rotation about its own axisrelative to the cam element, means for releasably locking said sleeveagainst bodily sliding movement in relation to said cam element, anoperating spindle pivotally mounted within said sleeve, a pivot pincarried by said operating spindle having its axis parallel, buteccentric to the axis of pivoting of said operating spindle, a dierelease lever mounted pivotally on the pivot pin, said die release leverbeing operatively connected to the body element so that said lever isadapted to be turned about said pivot pin to displace said cam and bodyelements relatively between die operating and die release positions forthe purpose of immediately effecting displacement of the dies into andout of operative position in relation to the work, said operatingspindle being adapted when pivoted in relation to the cam element uponwhich it is mounted, to displace said pivot pin bodily in relation tothe cam element between two operative positions corresponding todifferent predetermined, thread cutting depths, said die release leverbeing adapted to co-act with said pivot pin in transmitting said bodilymovement thereof to displace said body and cam elements relativelybetween said two operative positions, said operating spindle and saidsleeve having inter-engageable abutments adapted to secure the spindleagainst pivotal movement in relation to the sleeve so as to lock thepivot pin against bodily displacement relative to the cam element ineach of said two operative positions, said spindle being axiallydisplaceable in relation to said sleeve for the purpose of efiectingdisengagement between the inter-engageable abutments so as to permit ofthe spindle being turned relative to the sleeve and the pivot pindisplaced bodily between its two operative positions, and spring meansacting between the spindle and the sleeve for retaining the saidabutments in releaseable engagement with one another.

13. In a die stock for use in forming a screw thread, and of the kindcomprising a hollow body, a plurality of threading die elements eachdisplaceably mounted on the body for movement towards and away from theaxis of rotation of the die stock, a die displacing element mountedrotatably on said body with cam means operating between said diedisplacing element and said threading die elements, the provision of areaction member mounted slidably on the body for movement towards andaway from the axis of rotation of the die elements, displacing membermeans releasably connecting said die elements displacing member to saidreaction member, means adapted positively to lock said die elements intwo positions in relation to the said die stock axis, namely, a positionfor cutting a thread to the full depth and also in an intermediateposition for cutting a thread to less than the full depth, and saidconnecting means being adapted to transmit any reaction of the dieelements on the die displacing member directly to said reaction memberin each of said two positions of said die elements.

ARTHUR TREVENA.

REFERENCES CITED The following references are of record in the file orthis patent:

UNITED STATES PATENTS

